Re: A problem with 1,8-diaminonaphthalene synthesis

"Albert Ruggi" <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> Hi all,
> I have a big problem with this reaction:

> 1,8-dinitronaphthalene > 1,8-diaminonaphthalene

> I attempt to reduce the dinitro with HCl and Fe, but when I put inside NaOH
> I have a precipitate like-black-green coloured (maybe Fe(OH)2) and a liquid
> red/brown dark. I attempt to extract with CHCl3 and i had a red coloured
> organic phase.
> I hope somebody coul help me, because I don't know what's the problem but i
> know 1,8-diamino it's a yellow solid and so i don't understand what's
> happened in my beacher!
> I need to synthetize the 1,8-diamino because it's an intermediate product to
> have perylene.
> Tank you in advance for any help and sorry for my terrible english!

> Albert Ruggi
> [EMAIL PROTECTED]
> www.chimicavita.cjb.net



Hi Albert,
the problem you have is very probably due to complex formation between
ferrous ions and the diamin, which is an perfect ligand for forming
complexes. What you should do, is the removal of the iron ions from
the solution by precipitation. For example you could take hydrogen
sulfide to precipitate the iron as iron sulfide, after removing of the
prcipitate you should be able to isolate the 1,8-diamine. But at all,
reduction of a nitro compound with iron is a very ugly way to do this
reaction. It is far better to use SnCl2 or Sn in concentrated hydrogen
chloride acid. The Sn salts will precipitate as insoluable
Sn(IV)-oxide, even in acidic environment, than you could isolate the
diamin in the filrate after neutralising the acid in the filtrate, and
extracting the diamine into an organic solvent.
The use of Sn also will give a much more better yield, since the Fe
approach is sometimes accompanied by uncomplete reduction, resultion
in the formation of nitroso compounds and things like
this.............


Good luck



-- 
Paul J. Franklin(moderator - sci.chem.organic.synthesis) 
http://organicworldwide.net/sci.chem.organic.synthesis
Georgia State University <[EMAIL PROTECTED]>
Atlanta, GA